1. Field of the Invention
The present invention relates in general to a marine propulsion system, and in particular to a transmission for a propulsion system of an outboard drive.
2. Description of Related Art
Many outboard drives of marine watercrafts employ a counter-rotating propeller system operated by a forward-neutral-reverse transmissions. Such propulsion systems are used in both outboard motors and in stern drive units of inboard/outboard motors.
These transmissions typically include a driving pinion and a pair of oppositely rotating driven bevel gears. A front dog clutch of a dual clutch assembly is interposed between the pair of oppositely rotating gears. The clutch drives a inner propulsion shaft through a spline connection. The inner propulsion shaft in turn drives a rear propeller.
The transmission also includes a second dog clutch that is positioned on the rear side of the rear driven gear. The rear clutch selectively engages corresponding teeth formed on a hub of the rear gear to drive an outer propeller shaft. The outer propulsion shaft in turn drives a front propeller.
An actuator mechanism selectively moves the clutches into engagement with the driven gears. A front pin, which extends transversely to the axis of the inner shaft, directly connects the front dog clutch to a plunger of the actuator mechanism. A rear pin, which also extends transversely to the inner shaft axis, couples the rear clutch to the plunger. The ends of the rear pin extend into an annular groove formed within the rear gear body and are captured within the groove. During at least one drive condition (e.g., a forward drive condition), the rear pin and the rear clutch rotate in opposite directions at high rotational speeds.
Although this prior coupling design between the plunger and the rear clutch allows the plunger to move the clutch while permitting the rear clutch to rotate relative to the plunger and rear pin, the prior coupling design tends to produce significant friction and wear between the rear pin and the rear clutch. Prior attempts the journal the pin ends within the annular groove also have proven less than adequate in reducing friction and wear between these components.